Electric circuit controlling device of the thermal overload type



1936- E. N. LIGHTFOOT ELECTRIC CIRCUIT CONTROLLING DEVICE OF THE THERMALOVERLOAD TYPE Filed Dec. 9, 1935 2 Sheets-Sheet 1 Jan. 14, 1936. E N,LIGHTFQQT 7 2,027,541

ELECTRIC CIRCUIT CONTROLLING DEVICE OF THE THERMAL OVERLOAD TYPE FiledDec. 9, 1953 2 Sheets-Sheet 2 I I9 l9 B 5f !4 0 Patented Jan. 14, 1936"UNITED STATES ELECTRIC CIRCUIT CONTROLLING DEVICE OF THE THERMALOVERLOAD TYPE Edwin N. Lightfoot, Wauwatosa, Wis., assignor toCutler-Hammer, Inc., Milwaukee, Wis., a corporation of DelawareApplication December 9, 1933, Serial No. 701,582

9 Claims.

This invention relates to improvements in electric circuit controllingdevices of the thermal overload type, and more particularly to suchdevices having the thermal overload elements thereof immersed in oil orother insulating liquid.

In the use of electric circuit controlling devices such aselectromagnetically operable switches there is an increasing demand fora greater degree of protection against special conditions in service,aswhere the switches are to be used in the presence of corrosive gases orvapors, or where there are explosion hazards. These conditions sometimesrequiresubmersion of the circuit controlling device in a liquidinsulating medium such as oil, and when a thermal overload deviceisemployed the same must also be submerged. Such immersion involvesdifficulties in handling overload devices of thethermal type whichfunction through the development of heat in the active element withresultant tripping of the overload contacts when some definitetemperature is reached.

The dissipation of heat from the source of heat (particularly such asmall source as is employed in thermal overloads) in oil is muchdifferent from and greater than the dissipation of heat in air. If theusual air-operated thermal overload is placed in oil, the rapiddissipation of heat so increases its required tripping-current under 30continuous conditions that the ratio of its burnout-current value to itsnormal-current value is so reduced as to render it commerciallyimpractical. v My invention has for an object to provide an oil-immersedelectric circuit controlling device of the thermal overload type whereinthe dimculties aforementioned are obviated.

Another and more specific object is to provide an oil-immersed thermaloverload device of simple and eflicient character. I

Another object is to provide novel means for effecting resetting of thethermal overload device after response thereof.

- Other objects and advantages of the invention will hereinafter appear.

I have discovered that by placing the heat source of the thermaloverload device in such an environment as to reduce the heat dissipationin oil to a permissible amount a practicable operat ing device will beprovided. This is accomplished by locating the overload heating elementin an inverted (open bottom) recess, thus providing for minimizing orreducing the convection flow of heated oil away from the heatingelement, whereby. the heat is localized with respect to the oil withinthe recess. The recess is preferably just large enough to receive thenecessary parts of the thermal overload device. The walls of the recesspreferably consist of a material of relatively low heat conductivity,that is to say, of molded insulating material rather than metal; andsaid walls are likewise preferably of considerable thickness,bothfeatures tending to reduce or minimize conduction of heat to the mainbody of the oil.

When the thermal overload device is initially immersed. in oil theaforementioned inverted recess will trap a quantity or bubble of air,which if allowed to remain would tend to make operation of the thermaloverload device irregular. For venting of such air, I prefer to providea small opening or passage through the upper end wall of said recess.This passage permits the air to leave the recess but does not permit aflow of oil suflicient in volume to impair the result desired andcontemplated.

Where a thermal overload device of the fusible alloy type is employed, Ihave found that access of the oil to the fusible alloy while in itsmolten condition tends to reduce the useful life of the alloy. 1therefore propose to so construct the container for the alloy as tominimize access of oil to the latter. This is accomplished by providinga container having a closed lower end,- instead of an open-end'tube ofthe character employed in well known forms of thermal overload devicesof the fusible'alloy type adapted for operation in air.

The accompanying drawings illustrate an embodiment of my invention whichwill now be described, it being understood that the embodimentillustrated is susceptible of modification within the scope of theappended claims.

In the drawings, Figure 1 is atop plan view of a thermal overload deviceof the fusible alloy type as constructed in accordance with myinvention,aportion of said device being shown in section for clarity ofillustration.

Fig. 2 is a view partly in said elevation, and

partly in vertical section on the line 2 of Fig. 1.

Fig. 3 is a bottom plan view of the'device shown in Figs. 1 and 2.

Fig. 4 is a vertical sectional view on the line H of Fig. l,certain ofthe parts being shown in elevation.

Fig. 5 is an enlarged vertical sectional view of certain of the elementsshown at the left-hand side of Fig. 2.

Fig. 6 is a side elevation of an oil-immersed electromagneticallyoperable switch having my improved form of thermal overload deviceassociated therewith,the oil receptacle or container being shown insection. v

Fig. 7 is a fragmentary elevational view taken at right angles to theview of Fig. 6, and likewise showing the oil receptacle or container insection, and

Fig. 8 is a schematic and diagrammatic view illustrating an adaptationof my improved thermal overload device, in combination with anelectromagnetically operable switch and a pushbutton station, to controlthe energization and deenergization of a suitable translating device.

Referring more particularly to Figs. 1 to 5 of the drawings, the numeralI0 designates a molded insulating base'which serves as a supporting basefor the several elements of my improved thermal overload device. Certainof the parts of said thermal overload device are in general quitesimilar to the parts disclosed in the patent of C. W. Kuhn, No.1,894,404, dated January 17, 1933, for an electric control device.

The device specifically illustrated in said Kuhn Patent No. 1,894,404 isintended for operation in air, and the same is entirely unsuited foroperation when immersed in oil or other insulating liquid, for reasonshereinabove set forth.

To provide for attainment of the results contemplated by me, the base I0is provided with a pair of substantially cylindrical recesses II and I2which open to the lower surface thereof, as best illustrated in Figs. 2,3 and 5. Located centrally within said recesses I I and I2 and dependingfrom the upper end walls thereof are a pair of metal cup members orcylinders I3 and I4 of like form. The upper end wall I2 of recess I2 isprovided withan opening comprising a lower cylindrical portion I2 intowhich the vertically grooved or milled portion I i of member I4 ispressed ordriven', and a relatively larger upper cylindrical portion I2within which the flange I4 of hexagonal contour (Fig. 2) is adapted toseat with a press fit in a relation substantially flush with the uppersurface III of said base. In this manner member I4 is restrained againstrotation relatively to base I 0. Member I4 is provided with a closedlower end I I and the same is recessed as shown to provide therelatively small cylindrical portion the relatively larger cylindricalportion I4 and the still larger cylindrical portion I4 which opens tothe upper surface of base I0.

A metal member I5 is provided with cylindrical portions I5, I5 and I5respectively adapted to rotatably bear within the aforementionedportions I4, I4 and I4. The portion I 5 is of substantially lessdiameter than the portion I 4 within which it bears to provide forinterposition of a body or film of a fusible or eutectic alloy I6, whichalloy when solid is adapted to restrain ririember I5 against rotationrelatively to member Prior to assembling the members I I, I5 I prefer toinsert within the recess in member I4 a suitable quantity of the alloyin the form of a length of wire of small cross sectional dimensions. Thealloy'isv then fused by application of heat from a suitable source (suchas a gas jet or blow-torch) and while the alloy remains in fused,

or molten condition the member' I5 is inserted downwardly into therecess in member I 4. Member I4 is provided in the wall thereof with arelatively small opening I4 throughwhich any excess quantity of thealloy is permitted to escape to limit the height of the body of alloywithin the portion I4 of said recess. Opening ll also provides forinspection or observation of the body of I alloy I6. By reason of theclosed lower end I4 of member II the oil within which the overloadimizing the area of contact between the oil and the alloy the usefullife of the latter is greatly increased, as compared with an arrangementwherein the oil has access to the body of the alloy ateach end thereof.Also the portion I5 is preferably vertically grooved or milled orotherwise roughened as illustrated.-

Member I5 is provided at the upper end thereof with a cylindricalportion I5 which provides a bearing for a rotatable insulating blockI1,- the insulating material of which said block is formed beingpreferably of the phenol-formaldehyde condensation type soldcommercially under the trade name of Bakelite. Block H is pro.-

' vided with a substantially cylindrical recess I1 to accommodate thevertically toothed cylindrical portion I5 of member I5,the latter beingprovided with a circular flange I5 against which the wall of recess I1is adapted to bear to assist in centering block II, as best illustratedin Fig. 5. Recess I! is open at one side thereof to provide forengagement of a spring pawl or latch I8 with the teeth on portion I5,-said latch being secured to block I 'I as by means of a screw I8having threaded engagement with a recess formed in the latter. Block I!is provided at the side thereof opposite to latch I8 with a resilientcontact member I9 having a tip riveted or otherwise'secured to the freeend thereof as shown at I9 said tip being movable into and out ofengagement with a. stationary contact 20 having a wiring terminalrepresented by the clamping nut 20 which threads onto the securing bolt20'. Member I9 is secured to block I! as by means of a screw I9 whichthreads into a recess provided in the latter. Secured to base I0 as bymeans of a screw 2I is a bracket 2| having an upwardly offset horizontalportion 2| which overlies block II to retain the same in bearingengagement with member I5. A similar, but right-hand. block 22 isrotatably mounted in a like manner upon the rotatable member (not shown)associated with the alloy-containing bearing member I3 (Fig. 3), saidblock having attached thereto a resilient contact member 25 whose tip 23is movable into and out of engagement with stationary contact 24 havinga wiring terminal nut 2 I threaded onto-securing bolt 24. 253

Contact member 23 issecured to block 22 as by means of a screw 23*. Alsosecured to base II) ,as by means of a screw 25 is a bracket 25 having anupwardly offset horizontal portion 25 to retain block 22 in assembledposition. Interposed between blocks I I and 22 at the rear. endsthereofis a coiled compression spring 26 (Fig. 1) whereby block I1 isbiased in a counterclockwise direction and block 22 is'blased in aclockwise direction to effect disengagement of the contact'tips I9 and23 from the respective contacts 20 and 24. Blocks I1 and 22 arepreferably provided with integral projections or abutments whichenter-the respective ends of spring 26 to assistin positioning thelatter,'-the projection on block 22 being shown at 22'? in Fig. 1, andthe projection on block I! being shown at II? in Fig. 4. Spring 26 islikewise provided at opposite ends thereof with-straight portions (notshown) which to abut.

13 and 23 to further assist in positioning the spring. In order toinsure a good electrical connection between contact members 49 and 23 Iprovide'a suitable length of multiple-strand flexible copper wire 21 theends of which are likewise clamped by the heads of screws l 9* and 23The intermediate portion of wire 21 is preferably passed through thecoils of spring 26 to insure against fouling or excess bending thereofwhen in use. vided with shoulders ll and 22 engageable with the verticalportions of brackets 2| and 25 to limit the degree of movement thereoffor efiecting engagement of contact tips I 5 and 23* with contacts 20and 24. l

The means-for effecting engagement of the aforementioned contactscomprises essentially a cone-shaped cam 28 which is normally positionedwithin a cylindrical passage Ill provided in base l0,said passage beingenlarged at the lower end thereof, as indicated at Ill to provide ashoulder against whicha washer 28 is adapted Cam 28 is provided with ashank 28 which is slidable through washer 28 and a coiled compressionspring 23 is interposed between Washer 28 and a second washer 23 whichis restrained against downward displacement as by means of a split lockwasher 23 of well known form. The upper end of cam 28 is provided with atapped recess to receive-the lower end of a threaded adjusting rod orconnector 29 which is secured in adjusted relation to cam 23 as by meansof a lock-nut 23=,-the other end of said connector being adjustablysecured by the locknut 23 within the tapped recess in the lower end ofan insulating member 33 forming part of the pull-rod 30 (Figs. 6 and 7).Thus assuming open positioning of the contacts, as'shown in Fig. 1, thecam 28 upon upward movement thereof is adapted to engage and spread thecontact members I! and 23 and the blocks l1 and 22 which carry the same.The pawl l8 carried by block I! will cooperate with the teeth l5 ormember I5 to retain the contact tip IS in engagement with contact 20,and

the corresponding parts (not shown) associated with block 22 willlikewise act to retain contact tip 23 in engagement with contact 24.Said sets of contacts will respectively remain closed pending fusing ofthe alloy l6 within the container H or the alloy within container l3,itbeing understood that upon fusing of the respective bodies of the alloythe blocks l I and 22 will be free to move under the bias of spring 23to effect opening of the respective pairs of contacts.

The means for effecting fusing of the alloy within containers l3 and Hcomprises overload coils of resistance wire 3| and 32 located withinrecesses II and 12 respectively. Said overload coils 3| and 32 arerespectively provided with termlnals 31*, 3| and 32, 32' for connectionof each thereof in series in the supply lines of a translating device,such as the motor 33 in Fig. 8. The base It is adapted tobe positionedwithin a body'of oil with the recesses H and i2 opening downwardly, asindicated in Fig. 2. It is thus apparent that portions of the body ofoil will enter the respective recesses, 'and the heat generated by theheating coils 3| and 32 will be localized in said portions of the bodyof oil to permit transfer of the proper degree of heat to the bodies ofalloy located within the containers l3 and 14,- the degree of diffusionof the heat so generated throughout the main body of the oil beingminimized by the arrangement of said recesses H Blocks l1 and 22 arerespectively proand I2 which prevents flow of oil from said recesses asan incident to the convection currents generated therein.

Also as aforeindicated it is desirable to eliminate or vent any air orgas entrapped within the recesses H and I2, and I accordingly providesaid recesses with relatively small passages I I and I2 which extendfrom the upper end walls thereof and open onto the upper surface of baseIll. Said passages H and I2 thus permit escape of air or gas entrappedwithin said recesses, whereas the same are of suclismall cross sectionas to prevent substantial upward flow or displacement of the heated oilfrom said recesses. While I prefer to effect venting of entrapped air bythe means illustrated, it will be apparent to those skilled in the artthat a similar result might be obtained by providing for tilting thebase III or even temporarily inverting the same during or afterimmersion thereof within the body of oil.

In Figs. 6 and '7 I have shown my improved thermal overload device ascombined with an electromagnetically operable switch of known form. Saidswitch, which is designated in general by the numeral 34 is of thecharacter described and claimed in the patent of C. W. Kuhn, No.1,981,555, dated November 20, 1934, to which reference may be had for amore detailed description of said switch. Said switch in Figs. 6 and 'lis shown somewhat diagrammatically, and includes a magnet winding 34,and an armature 34 controlled by said winding. Said armature carriescontacts (not shown) for cooperation with suitable contacts carried uponthe base of the switch. The wiring is omitted from the switch and'theoverload device in Figs. 6 and l,- but the manner of wiring the variouselements is shown diagrammatically in Fig. 8. The switch 34'is supportedby a cast metal bracket 35, which bracket preferably includes a topplate 35' and means 35* to provide for attachment thereof to a panel,wall or other suitable support. Attached to bracket 35 at the lower endthereof is a substantially U--shaped sheet metal supporting element 36,to the spaced arms 33 36 of which the base In is attached as by means ofbolts 36, 36, as illustrated, for support of base I0 in a horizontalplane with-the recesses H, I2 opening to the lower surface thereof. BaseI0 is provided with end posts or projections Hi I0 through'which bolts36, 36 are adapted to pass. The pull-rod 30 is adapted for operation inthe manner aforeindicated to effect resettingof the thermal overloaddevice after response thereof.

The numeral 31 designates a tank or container for a body 38 of oil orother insulating liquid within which the switch and overload device areto be immersed. Tank 31 is adapted to be de tachably connected to covermember 35'- by swing-bolts or other suitable means (not shown) ,--theupper end of pull-rod 33 having a handle 30'' which is removable andadjustable.

push-button switch 40 a circuit is completed which may be traced fromline L by conductors 4| and 42 through switches 40 and 39, conductor 43through the contacts of the overload device, and by conductor 44 throughsaid winding 34 to line L. Switch 34 thus responds to complete thecircuit for motor 33. The auxiliary contacts 348 of switch 34 uponclosure thereof shunt the pushbutton switch 40 to provide a maintainingcircuit for winding 34. The circuit of winding 34 will be maintainedpending manual opening of push button switch 39 or automatic opening ofone or both of the pairs of-overload contacts I9, 20 or 23, 24 due tothe aforedescribed heating effect of the overload coils 32, 3|,respectively. The push-button station is shown diagrammatically as beingprovided with a'housing or enclosure 45 of the gas-tight orexplosion-proof type. Enclosures of this character are well known in theart, and further description thereof is deemed unnecessary. Thearrangement of course will be such as to provide for operation of thepush-button switches 39, by means accessible from the exterior of thehousing. The bushbutton switches 39, 40 may if desired be located at apoint remote from the switch 34 and the overload device, in which eventan explosionproof casing for said push-button switches may be consideredunnecessary.

While I have described my invention with specific reference to thermaloverload devices of the fusible alloy type, it isto be understood thatcertain features herein disclosed are equally applilocated within saidrecess.

. acting to localize the heat generated by said heating element to thatportion of the body of liquid 2. In a device of the character described,in combination, a container, a body of insulating liquid in saidcontainer, an electro-thermally re-' sponsive circuit breaker immersedin said liquid,

said circuit breaker including a base having a recess formed inthe lowersurface thereof, a

thermally responsive elementjand an electric heating element locatedwithin said recess, the walls of. said recess acting to localize theheat generated by said heating element to that porsponsive circuitbreaker immersed in said liquid, said circuit breaker including aninsulating base having a recess in the lower surface thereof, a

' thermally responsive element and an electric heating element locatedwithin said recess, the walls of said recess acting to localize the heatgenerated bysaid heating element to that portion of the body of liquidlocated within said recess, and the upper end wall of said recess havinga relativelysmall passage extending therethrough to provide for.automatic venting of any air or gas entrapped within said recess whilepreventing any substantial flow of liquid from the latter. 1

4. In a thermal overload device, in combination, a body oil-insulatingliquid such as 011, an insulating base to be totally submerged in saidoil, said base having a recess formed therein and opening to the lowersurface thereof, a hollow metal member having a closed lower endextending downwardly from the upper end wall of said.

recess, the upper end of said memberbeing nonrotatably secured to saidbase and opening to the upper surface of the latter, a metal memberhaviIE a body of solder interposed between the same and said hollowmember and adapted when solid to prevent rotation of said metal member,means tending. to efiect rotation of said metal member in onedirection,and an electric wire heating coil located within said recess andsurrounding said hollow member, said coil when energized being.

adapted to heat the oil within said recess to effect a correspondingdegree of heating of said body of solder, the walls of said recessacting to prevent substantial displacement of the heated oil therefromunder the influence of convection currents generated therein.

5. In a thermal overload device of the character described, incombination, a molded insulating base having a substantially cylindricalrecess opening to the lower surface thereof, a thermally responsive unitcomprisinga hollow metal member having a' closed lower end, said memberbeing non-rotatably supported by and depending from the upper end wallof said recess and having its upper end opening'to the upper surface ofsaid base, a shank member insertable downwardly into said hollow memberand having a rotatable bearing engagement with the latter, meanscomprising a quantity of eutectic alloy interposed between said shankmember and said hollow member to normally restrain the former I againstrotation with respect to the latter, means biasing said shank member forrotation thereof in one direction, a body of insulating liquid withinwhich said thermal overload device is submerged, and an electric heatingelement located within said recess in spaced relationship to saidcylindrical member, said recess having a relatively smallpassageextending upwardly through the upper end thereof, said passageproviding for automatic venting of any air or gas entrapped within saidrecess while preventing substantial displacement of said liquid fromsaid recess under the influence of convection currents generatedtherein.

6. In a thermal overload device of the character described, incombination, a molded insulating base having a cup-shaped recess openingto the lower surface thereof, a thermally responsive unit comprising asubstantially cylindrical member having a closed lower end, said memberbeing non-rotatably supported by and depending from the upper end wallof said recess, an electric wire heating element located within saidrecess in spaced relationship to said cylindrical member,

of said base and having a shank extending downwardly into saidcylindrical member, means comprising a fusible medium interposed betweensaid shank and said member to normally restrain the former againstrotation, a stationary contact and a movable contact, said movablecontact being biased away from said stationary contact, a pawlassociated with said movable contact and a toothed wheel exposed uponthe upper surface 2,027,541 gageable with toothed wheel to restrainsaid' movable contact against movement under its bias pending a givendegree of heating of said fusible medium, a body of insulating liquidwithin which said thermal overload device is submerged, a portion ofsaid body of liquid being adapted to fill said recess, and the walls ofsaid recess acting to prevent substantial displacement of said portionof said body of liquid under the influence of convection currentsgenerated therein to facilitate transmission of said heat to saidfusible medium.

7. In a; thermal overload device of the character described, incombination, a molded insulating base having a cup-shaped recess openingto the lower surface thereof, a thermally responsive unit comprising asubstantially cylindrical member having a closed lower end, said memberbeing non-rotatably supported by and depending from the upper end wallof said recess, an electric wire heating element located within saidrecess in spaced relationship to said cylindrical member, a toothedwheel exposed upon the upper surface of said base and having a shankextending downwardly into said cylindrical member, means comprising afusible medium interposed between said shank and said member to normallyrestrain the former against rotation, a stationary contact-and a movablecontact, said movable contact being biased away from said stationarycontact, a pawl associated with said movable contact and engageable withsaid toothed wheel to restrain said movable contact against movementunder its bias pending a given degree of heating of said fusible medium,a body of insulating liquid within which said thermal overload device issubmerged, a portion of said body of liquid "being adapted to fill saidrecess, the walls of said recess acting to prevent substantialdisplacement of said portion of said body of liquid under the influenceof convection currents generated therein to facilitate transmission ofsaid heat to said fusible medium, and a pull-rod extending upwardlythrough and beyond said body of insulating liquid to provide forresetting of said overload device and consequent re-engagement of saidcontacts after response of the former,

8. In a system of the character described embodying an electrictranslating device, an electromagnetieally operable switch to controlenergization and de-energization of said translating device, acontainer, and a body of insulating liquid located within saidcontainer, said switch and the electromagnetic means therefor beingsubmerged within said body of liquid, in combination, anelectrothermally responsive overload device also submerged within saidbody of liquid and adapted upon response thereof to effect interruption'of the energizing circuit of said switch, saidoverload device includinga base having a'recess opening downwardly, a thermally responsiveelement and an electric heating element located within said recess, andmanually operable means extending upwardly through said body of liquidand accessible from the exterior of said container for effectingresetting of said overload device after response thereof.

9. In a system of the character described embodying an electrictranslating device, an electromagnetically operable switch to controlenergization and de-energization of said translating device, acontainer, a body of insulating liquid located within said container,-said switch and the electromagnetic operating means therefor beingsubmerged within said body of liquid, an electro-thermaliy responsiveoverload device, a push-button station located at a point spaced fromsaid container, said station including a normally open push buttonswitch and a normally closed push-button switch, said normally openpush-button switch when closed being 1 adapted to cooperate with saidnormally closed push-button switch andsaid overload device to initiallycomplete the energizing circuit of said electromagnetically operableswitch, and said normally closed push-button switch being 011-- erableat will independently of said overload device to effect interruption ofthe energizing circuit of said electromagnetically operable switch, thecombination wherein said electrotherma'lly responsive overload device isalso submerged within said body of liquid and adapted upon responsethereof to effect interruption of the energizing circuit of said switch,said over- 40 load device including a molded insulating base having arecess opening to the lower surface thereof, a thermally responsiveelement and an electricheating element located within said recess,manually operable means extending upwardly through said body of liquidand accessible from the exterior of said container for effect- I ingresetting of said overload device after re- 1 sponse thereof, andanexplosion-proof housing within which the contacts of said push-button toswitches are enclosed. Z

N. LIGHTZEOOT.

.the word said read side; page 2, second column, line 5, for contractread contact page 3, first column, lines 14 and 44 respectively, forfl5read 19; same page and Certificate of Correction Patent No. 2,027,541.January 14, 1936. EDWIN N. LIGHTFOOT It ishereby certified that errorsappear in the, printed specification of the above numbered patentrequiring correction as follows: Page I, second column,- line 44, for

column, line 34, strike out the word the; page 4, first column, line 24,for the K syllable bushread push; and that the said Letters Patentshould be read with these corrections therem that thesame' Iney conformto the record of the case in the Patent Ofiice. I

Signed and sealed this 19th day of May, A. D. 193(5.

. 8m} LESLIE FRAZER,

Acting Commissioner of Patents.

Certificate of Correction Patent No. 2,027,541. 4 January 14, 1936.

v EDWI N N. LIGHTFOOT It is hereby certified that errors appear in the.printed specification of the above numbered patent requiring correctionas follows: Page 1, second column, line 44, for .the word "saidroadside; page 2, second column, line 5, for contract read contact; page3, first column, lines 14 and 44 respectively, for"15 read 19"; samepage and column, line 34, strike out the word the".; page 4,'firstcolumn, line 24, for the llable bushread push; and that the said LettersPatent'should be read with ese corrections therein thatthesame' conformto the record of the case in the Patent Ofiioe. V

Signed and sealed this 19th day of May, A. D. 193$).

[sml' LESLIE FRAZER,

- I Acting Commissioner of Patents.

